1994 Fiscal Year Final Research Report Summary
Simultaneous measurement of the structure and function of the artery using an intravascular ultrasound transducer.
| Project/Area Number |
05680749
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| Research Category |
Grant-in-Aid for General Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Research Field |
Biomedical engineering/Biological material science
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| Research Institution | Hokkaido University |
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Principal Investigator |
YAMAMOTO Katsuyuki Hokkaido University, Faculty of Engeneering, Professor, 工学部, 教授 (10088867)
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| Co-Investigator(Kenkyū-buntansha) |
OKAMOTO Eiji Hokkaido University, Faculty of Engineering, Instructor, 工学部, 助手 (30240633)
SHIMIZU Koich Hokkaido University, Faculty of Engineering, Associate Professor, 工学部, 助教授 (30125322)
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| Project Period (FY) |
1993 – 1994
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| Keywords | Ultrasonic measurement / Intravascular ultrasound / Arterial elasticity / Sound velocity / Correlation measurement / Blood velocimeter |
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| Research Abstract |
We studied intravascular ultrasound techniques for simultaneous measurements of structure, elasticity and blood flow with respect to the artery. The following results were obtained
We measured the acoustic properties of arterial walls such as sound velocity, acoustic impedance and reflectivity of the wall, because these were not sufficiently available even if essential for ultrasonic measurement of the artery. The sound velocity of a thin layr like an arterial wall was successfully determined using a spectrum analysis of RF echo signals. As for acoustic impedance there was only abount 1% difference between the wall and the blood. This resulted in large variation of the reflectivity even if the impedance change was relatively small.
We then developed an intravascular ultrasound imaging system for the measurement of both the structure and elasticity of the artery. Pulsatile change in luminal area of the artery was obtained from its cross-sectional images and used for determining the elasticity. To improve the measurement accuracy, the elasticity was calculated from the slope of a regression line of luminal area to blood pressure. Elasticity measurement with the developed method along the dog aorta showed comparable accuracy with a reference method which was specially designed for elasticity measurement.
In addition to the above measurements, we theoretically and experimentally studied a new technique for measuring a flow perpendicular to the axis of an ultrasound beam with a single transducer. With this technique we can measure a flow rate without additional transducer for velocity measurement. When RF echo signals are taken at a certain repetition rate, the transverse component can be determined from the peak value of the correlation. We conducted experiments to verify the validity of our method, using porous phantom placed on a turn table and flow of starch suspension in water within a tube. Experimental results agreed well with theoreticals.
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